Communication apparatus and automatic gain control

ABSTRACT

Provided is a communication apparatus including a first communication unit for performing communication using a carrier having a first frequency, a second communication unit having a plurality of antennas, for performing communication using a carrier having a second frequency, a first communication processing unit for processing a signal received by the first communication unit and causing to transmit a signal, and a second communication processing unit for processing a signal received by the second communication unit and causing to transmit a signal. The second communication processing unit includes a synchronization unit for specifying a start position of a second transmission request in which a plurality of transmission beam patterns are set in one packet based on information indicating reception initiation, and an automatic gain control unit for performing automatic gain control based on a first automatic gain control setting value.

TECHNICAL FIELD

The present invention relates to a communication apparatus and anautomatic gain control method.

BACKGROUND ART

In recent years, for example, various apparatuses such as computers,e.g., a notebook PC (Personal Computer), or television receivers havemore functions and apparatuses having a function of enabling wirelesscommunication with other apparatuses have become widespread. Here,wireless communication between such apparatuses is performed, forexample, using a carrier (electromagnetic waves) having a predeterminedfrequency, such as a 5 GHz band.

Meanwhile, in recent years, technology for increasing a communicationspeed of wireless communication using a carrier having a higherfrequency than a millimeter wave has been developed. Here, themillimeter wave refers to, for example, a carrier having a wavelength of10 mm to 1 mm and a frequency of 30 GHz to 300 GHz. Accordingly, forexample, when a millimeter wave such as a 60

GHz band carrier is used for communication, channels can be allocated inunits of GHz such that the communication speed can be higher compared tothe case in which a 5 GHz band carrier is used for communication.

In general, a millimeter wave such as the 60 GHz band carrier has acharacteristic in that the millimeter wave has a stronger directivity ora greater attenuation resulting from reflection than the 5 GHz bandcarrier. Thereby, communication using the millimeter wave such as the 60GHz band carrier is mainly performed using a direct wave or aonce-reflected wave. The millimeter wave such as the 60 GHz band carrierhas a further characteristic in that the millimeter wave has a higherfree space propagation loss than the 5 GHz band carrier. Accordingly, ingeneral, the communication using the millimeter wave has a shortercommunication distance than communication using the 5 GHz band carrier.

Meanwhile, technology related to communication using a carrier havingdirectivity has been developed. Technology of providing three or moreantennas having different set directivities and selectively processingany signal received by each antenna may include, for example, PatentLiterature 1.

Citation List Patent Literature

Patent Literature 1: Japanese Patent Application Laid-open PublicationNo. 2000-224139

SUMMARY OF INVENTION Technical Problem

In the conventional technology of providing three or more antennashaving different set directivities and selectively processing any signalreceived by each antenna (hereinafter, referred to as “conventionaltechnology”), an AGC (Automatic Gain Control) circuit is included foreach antenna.

When a communication apparatus includes an AGC circuit, thecommunication apparatus generally performs, for example, automatic gaincontrol at a head of a packet (data). The communication apparatusperforms the automatic gain control of the packet using an automaticgain control setting value (hereinafter, referred to as “AGC settingvalue”) set by the automatic gain control to the end. Accordingly, whena packet having single directivity is processed, the communicationapparatus may perform the automatic gain control normally.

However, a signal received by the communication apparatus does notnecessarily have the single directivity. For example, the communicationapparatus may receive a transmitted signal in which a plurality ofdirectivity patterns are set in one packet by an external apparatus.Here, when a plurality of directivity patterns are set in one packet,reception powers in the communication apparatus may differ, for example,by tens of [dB] due to set directivities. In the above case, since adynamic range of the received signal is very great, the communicationapparatus using the AGC setting value obtained in a head of the packetup to an end of the packet is limited. That is, in the above case, thecommunication apparatus cannot perform the automatic gain controlnormally on a received signal and, for example, the communicationapparatus cannot process the received signal normally, such that dataoutside the measurement range can be generated.

Here, in the conventional technology, an AGC circuit is included foreach antenna, but issues that may occur when a signal in which aplurality of directivity patterns are set in one packet is processed isnot considered. That is, in a communication apparatus to which theconventional technology has been applied (hereinafter, referred to as a“conventional communication apparatus”), issues may occur when thesignal in which a plurality of directivity patterns are set in the onepacket is processed. Accordingly, even when the conventional technologyis used, the communication apparatus may not process a received signalnormally.

The present disclosure is made in view of the above-mentioned problemand an object of the present invention is to provide a communicationapparatus and an automatic gain control method which are novel andimproved and which are capable of processing a packet having a widedynamic range in communication using directivity of antennas.

Solution to Problem

According to the first aspect of the present invention in order toachieve the above-mentioned object, there is provided a communicationapparatus including: a first communication unit for performing wirelesscommunication with an external apparatus using a carrier having a firstfrequency; a second communication unit having a plurality of antennas,for performing wireless communication with an external apparatus using acarrier having a second frequency having a stronger directivity and ahigher propagation loss than the carrier having the first frequency; afirst communication processing unit for processing a signal received bythe first communication unit and causing the first communication unit totransmit a signal; and a second communication processing unit forprocessing a signal received by the second communication unit andcausing the second communication unit to transmit a signal, wherein thesecond communication processing unit includes a synchronization unit forspecifying a start position of a second transmission request in which aplurality of transmission beam patterns are set in one packet, on thebasis of information indicating reception initiation delivered from thefirst communication processing unit based on a first transmissionrequest received by the first communication unit, the secondtransmission request being received by the second communication unit;and an automatic gain control unit for performing automatic gain controlon each transmission beam pattern based on a first automatic gaincontrol setting value corresponding to each transmission beam pattern,the first automatic gain control setting value being included in thesecond transmission request specified by the synchronization unit.

According to such a configuration, it is possible to process a packethaving a wide dynamic range in communication using directivity of anantenna.

Further, the communication apparatus may further include a receptionintensity derivation unit for deriving reception intensity for eachtransmission beam pattern based on the second transmission requestoutput from the automatic gain control unit; and a requested beampattern determining unit for determining a requested beam pattern to betransmitted to an external apparatus having transmitted the secondtransmission request from among the plurality of transmission beampatterns set in the second transmission request, based on a derivationresult from the reception intensity derivation unit.

Further, the communication apparatus may further include a setting valuestorage unit for storing a second automatic gain control setting valuecorresponding to the requested beam pattern based on a first automaticgain control setting value corresponding to the requested beam pattern,wherein the automatic gain control unit may perform automatic gaincontrol based on the second automatic gain control value when the secondtransmission request is not specified by the synchronization unit.

Further, the automatic gain control unit may perform the automatic gaincontrol using the first automatic gain control setting value or thesecond automatic gain control setting value as a fixed value or aninitial value.

Further, the setting value storage unit may store the second automaticgain control setting value having a higher set gain than the firstautomatic gain control setting value corresponding to the requested beampattern.

Further, the setting value storage unit may store the first automaticgain control setting value corresponding to the requested beam patternas the second automatic gain control setting value.

Further, a predetermined no signal period may be set between therespective transmission beam patterns among the plurality oftransmission beam patterns set in the second transmission request.

Further, the communication apparatus may further include a processingunit for causing to transmit requested beam pattern identificationinformation indicating the requested beam pattern to the externalapparatus having transmitted the second transmission request via thefirst communication processing unit.

According to the second aspect of the present invention in order toachieve the above-mentioned object, there is provided a communicationapparatus including: a first communication unit for performing wirelesscommunication with an external apparatus using a carrier having a firstfrequency; a second communication unit having a plurality of antennasdivided into a plurality of groups, for performing wirelesscommunication with an external apparatus using a carrier having a secondfrequency having a stronger directivity and a higher propagation lossthan the carrier having the first frequency; a first communicationprocessing unit for processing a signal received by the firstcommunication unit and causing the first communication unit to transmita signal; and a second communication processing unit for processing asignal received by the second communication unit and causing the secondcommunication unit to transmit a signal, wherein the secondcommunication processing unit includes a synchronization unit forspecifying a start position of a second transmission request in which aplurality of transmission beam patterns are set in one packet, on thebasis of information indicating reception initiation delivered from thefirst communication processing unit based on a first transmissionrequest received by the first communication unit, the secondtransmission request being received by the second communication unit;and an automatic gain control unit for performing, for each group,automatic gain control on the transmission beam pattern set in eachsecond transmission request received for each group based on a thirddifferent automatic gain control setting value set for each group.

According to such a configuration, it is possible to process a packethaving a wide dynamic range in communication using directivities of theantennas.

Further, the communication apparatus may further include a groupselection unit for selecting one group based on the second transmissionrequest for each group output from the automatic gain control unit; areception intensity derivation unit for deriving reception intensity foreach transmission beam pattern based on the second transmission requestcorresponding to the group selected by the group selection unit, thesecond transmission request being output from the automatic gain controlunit; and a requested beam pattern determining unit for determining arequested beam pattern to be transmitted to an external apparatus havingtransmitted the second transmission request from among the plurality oftransmission beam patterns set in the second transmission request basedon a derivation result from the reception intensity derivation unit.

According to the third aspect of the present invention in order toachieve the above-mentioned object, there is provided an automatic gaincontrol method including the step of specifying a position of apredetermined packet based on a first transmission request transmittedfrom an external apparatus using a carrier having a first frequency;specifying a start position of a second transmission request in which aplurality of transmission beam patterns defining beam-shaped directivityof a signal to be transmitted are set in one packet based on thespecified position of the predetermined packet, the second transmissionrequest being transmitted from the external apparatus using a carrierhaving a second frequency having a stronger directivity and a higherpropagation loss than the carrier having the first frequency; andperforming automatic gain control for each transmission beam patternbased on an automatic gain control setting value corresponding to eachtransmission beam pattern, the automatic gain control setting valuebeing included in the specified second transmission request.

It is possible to process a packet having a wide dynamic range incommunication using directivity of the antennas using such a method.

Advantageous Effects of Invention

According to the present invention, it is possible to process a packethaving a wide dynamic range in communication using directivity ofantennas.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is an illustrative diagram showing an example of a communicationsystem according to an embodiment of the present invention.

FIG. 2 is an illustrative diagram showing an example of a communicationprocess in the communication system according to an embodiment of thepresent invention.

FIG. 3 is an illustrative diagram showing an example of a firsttransmission request and a second transmission request according to anembodiment of the present invention.

FIG. 4 is a flow diagram showing an example of a synchronization processin the communication apparatus according to an embodiment of the presentinvention.

FIG. 5 is a flow diagram showing an example of a requested beam patterndetermination process in the communication apparatus according to anembodiment of the present invention.

FIG. 6 is an illustrative diagram showing an example of a secondtransmission request in which an AGC setting value is set.

FIG. 7 is an illustrative diagram showing an example of a secondtransmission request in which an AGC setting value is set according toan embodiment of the present invention.

FIG. 8 is an illustrative diagram showing an example of a secondtransmission request according to an embodiment of the presentinvention.

FIG. 9 is a flow diagram showing an example of a requested beam patterndetermination process in the communication apparatus according to anembodiment of the present invention.

FIG. 10 is an illustrative diagram illustrating an example of a groupselection process according to an embodiment of the present invention.

FIG. 11 is an illustrative diagram showing an example of a configurationof a communication apparatus according to a first embodiment of thepresent invention.

FIG. 12 is an illustrative diagram showing an example of a configurationof a second communication processing unit according to the firstembodiment of the present invention.

FIG. 13 is an illustrative diagram showing an example of a configurationof a second communication processing unit according to a modifiedexample of the first embodiment of the present invention.

FIG. 14 is an illustrative diagram showing an example of a configurationof a communication apparatus according to a second embodiment of thepresent invention.

FIG. 15 is an illustrative diagram showing an example a configuration ofa second communication processing unit according to the secondembodiment of the present invention.

FIG. 16 is an illustrative diagram showing an example of a configurationof a second communication processing unit according to a modifiedexample of the second embodiment of the present invention.

DESCRIPTION OF EMBODIMENTS

Hereinafter, preferred embodiments of the present invention will bedescribed in detail with reference to the appended drawings. Note that,in this specification and the drawings, elements that have substantiallythe same function and structure are denoted with the same referencesigns, and repeated explanation is omitted.

Further, hereinafter, a description will be given in the followingorder.

1. Approach according to Embodiment of the Present Invention

2. Communication Apparatus according to First Embodiment of the PresentInvention

3. Communication Apparatus according to Second Embodiment of the PresentInvention

(Approach according to Embodiment of the Present Invention)

An automatic gain control approach for processing a packet having a widedynamic range according to an embodiment of the present invention willbe described prior to explanation of a configuration of a communicationapparatus according to an embodiment of the present invention.

[Overview of Communication System according to Embodiment of the PresentInvention]

FIG. 1 is an illustrative diagram showing an example of a communicationsystem 1000 according to an embodiment of the present invention. Here,in FIG. 1, an example in which the communication system 1000 includescommunication apparatuses 100A, 100B, 100C, . . . , and thecommunication apparatus 100A and the communication apparatus 100B, andthe communication apparatus 100A and the communication apparatus 100Cperform communications, respectively is shown. In

FIG. 1, an example in which the communication apparatuses 100A and 100Bare notebook PCs and the communication apparatus 100C is a televisionreceiver is also shown. However, the communication apparatus accordingto an embodiment of the present invention is not limited to the notebookPC or the television receiver. Hereinafter, the communicationapparatuses 100A, 100B, 100C, . . . constituting the communicationsystem 1000 according to an embodiment of the present invention may becollectively referred to as a “communication apparatus 100.”

The communication apparatus 100 communicates with an external apparatususing two carriers: a carrier f1 having a first frequency, and a carrierf2 having a second frequency and having a stronger directivity and ahigher propagation loss than the carrier f1 having the first frequency.Here, the carrier having the first frequency according to an embodimentof the present invention includes, for example, a carrier whosefrequency widely used for data communication such as a wireless LAN(Local Area Network) is a 5 GHz band, but the present invention is notlimited thereto. Further, the carrier having the second frequencyaccording to an embodiment of the present invention includes, forexample, millimeter waves (or quasi-millimeter waves), but the presentinvention is not limited thereto.

Hereinafter, a case in which the communication apparatus 100 uses a 5GHz carrier as the carrier f1 having the first frequency and a 60 GHzcarrier as the carrier f2 having the second frequency will be describedby way of example. That is, hereinafter, a case in which communicationusing the carrier f2 having the second frequency is faster thancommunication using the carrier f1 having the first frequency will beillustrated. A communication method according to an embodiment of thepresent invention to be described below may also be applied, forexample, to a case in which the communication using the carrier f2having the second frequency is not faster than the communication usingthe carrier f1 having the first frequency.

[Communication Method in Communication System 1000]

The 60 GHz carrier f2 (the carrier having the second frequency) used forcommunication by each communication apparatus 100 in the communicationsystem 1000 has a stronger directivity and a higher propagation lossthan a 5 GHz carrier f1 (the carrier having the first frequency).Accordingly, there is a merit in that use of the carrier f2 having thesecond frequency for communication can realize faster communication thanuse of the carrier f1 having the first frequency for communication, butthere is a demerit in that the communication using the carrier f2 havingthe second frequency has a smaller communication distance than thecommunication using the carrier f1 having the first frequency.

Here, the communication apparatus 100 performs transmission of thecarrier f2 having the second frequency using directivity of an antenna.Since the carrier f2 having the second frequency can be transmitted in aspecific direction by performing the transmission of the carrier f2having the second frequency using the directivity of the antenna, thecommunication apparatus 100 can further increase a communicationdistance of the communication using the carrier f2 having the secondfrequency.

Here, the communication apparatus 100 includes, for example, a pluralityof antennas to create beam-shaped directivity, thereby increasing thecommunication distance of the communication using the carrier f2 havingthe second frequency. This is because use of a direct wave is moreeffective than use of a reflected wave in communication stability, forexample, due to a characteristic that the directivity is strong when afrequency of the carrier f2 having the second frequency is 60 GHz.Hereinafter, a beam-shaped directivity pattern according to anembodiment of the present invention is referred to as a “beam pattern.”

Methods of creating directivity using a plurality of antennas mayinclude, for example, a method of creating a beam with an array antenna,such as a method of determining a weight with a uniform distribution ora method of determining a weight with a Tayler distribution, but thepresent invention is not limited thereto.

When a signal is transmitted using the carrier f2 having the secondfrequency, a signal transmitted by the communication apparatus 100 at atransmission side (hereinafter, referred to as “transmission apparatus”)is not necessarily received by the communication apparatus 100 at areceiving side (hereinafter, referred to as “reception apparatus”)normally. This is because, when a beam pattern applied to the signaltransmitted by the transmission apparatus is not suitable forcommunication with the reception apparatus (e.g., when the transmittedsignal is not directed to the reception apparatus), the receptionapparatus may not receive the transmitted signal. Hereinafter, the beampattern applied to the signal transmitted by the transmission apparatus(or a signal to which the beam pattern is applied) may be referred to asa “transmission beam pattern.”

Accordingly, when a signal is transmitted by the carrier f2 having thesecond frequency, communication between the communication apparatusescannot be performed in the communication system 1000, for example, untilthe signal transmitted by the transmission apparatus (a signal to whichthe transmission beam pattern is applied) is directed to a receptionapparatus as a communication target. That is, when the signal istransmitted by the carrier f2 having the second frequency, much time maybe necessary until the transmission apparatus and the receptionapparatus, which is a communication target, can communicate with eachother.

Here, the communication system 1000 realizes more reliable datatransmission and reception using the carrier f2 having the secondfrequency by performing, for example, communications (a) to (c)(communication processes) between the transmission apparatus (onecommunication apparatus 100) and the reception apparatus (the othercommunication apparatus 100).

(a) The transmission apparatus transmits, to the reception apparatus,information of a plurality of transmission beam patterns capable ofbeing applied to a signal to be transmitted.

(b) The reception apparatus determines a beam pattern to be transmitted(hereinafter, “requested beam pattern”) from among the plurality oftransmission beam patterns. The reception apparatus transmitsinformation indicating the requested beam pattern (hereinafter referredto as “requested beam pattern identification information”) to thetransmission apparatus.

(c) The transmission apparatus transmits data with a carrier f2 having asecond frequency to which a transmission beam pattern corresponding tothe requested beam pattern has been applied, based on the receivedrequested beam pattern identification information.

According to the communications (a) to (c), the reception apparatusreceives data transmitted from the transmission apparatus with thecarrier f2 having the second frequency to which the transmission beampattern requested by the reception apparatus has been applied.Accordingly, the reception apparatus (one communication apparatus 100)may more reliably receive data transmitted by the carrier f2 having thesecond frequency from the transmission apparatus (the othercommunication apparatus 100).

Further, for example, when the transmission apparatus transmits a signalwith the carrier f2 having the second frequency, packet synchronizationmay not be performed since a signal received by the reception apparatusis small. In the above case, the reception apparatus may not specify theinformation of the plurality of transmission beam patterns transmittedby the transmission apparatus in (a).

Accordingly, in the above case, the reception apparatus may not performthe determination of the requested beam pattern according to (b) basedon the information of the plurality of transmission beam patternstransmitted by the carrier f2 having the second frequency.

Here, in the communication system 1000, the transmission apparatustransmits the signal by the carrier f1 having a first frequency and thesignal by the carrier f2 having the second frequency in synchronizationwith each other. Here, the synchronized transmission refers to, forexample, making a start position of a predetermined packet of the signalby the carrier f1 having the first frequency coincident with a startposition of a predetermined packet of the signal by the carrier f2having the second frequency and transmitting the signals.

This enables the reception apparatus to specify the start position ofthe predetermined packet of the signal by the carrier f2 having a secondfrequency based on the result of receiving the signal by the carrier f1having the first frequency. Accordingly, the reception apparatus mayperform the determination of the requested beam pattern according to (b)based on the signal by the carrier f2 having the second frequencytransmitted in synchronization with the signal by the carrier fl havingthe first frequency.

A communication process according to an embodiment of the presentinvention will be described in greater detail. FIG. 2 is an illustrativediagram showing an example of a communication process in thecommunication system 1000 according to an embodiment of the presentinvention. Here, FIG. 2 shows an example of a communication processaccording to communication between the communication apparatus 100A andthe communication apparatus 100B shown in FIG. 1. FIG. 2 also shows acase in which the communication apparatus 100A plays a role of areception apparatus and the communication apparatus 100B plays a role ofa transmission apparatus. Further, the communication apparatus 100according to an embodiment of the present invention may play roles ofboth the transmission apparatus and the reception apparatus.Accordingly, the communication apparatus 100A may play a role of thetransmission apparatus and the communication apparatus 100B may play arole of the reception apparatus. In FIG. 2, a case in which the firstfrequency is 5 GHz and the second frequency is 60 GHz is also shown.

The communication apparatus 100B synchronizes and transmits an RTS(Request to Send) packet at 5 GHz and an RTS packet at 60 GHz (period ain FIG. 2). Hereinafter, the RTS packet having the first frequency maybe referred to as a “first transmission request” and the RTS packethaving the second frequency may be referred to as a “second transmissionrequest.”

FIG. 3 is an illustrative diagram showing an example of the firsttransmission request and the second transmission request according to anembodiment of the present invention. Here, FIG. 3 shows a case in whichthe first frequency is 5 GHz and the second frequency is 60 GHz.

As shown in FIG. 3, the transmission apparatus makes the start positionof the DATA portion of the RTS packet at 5 GHz coincident with a startposition of BeamTrainingField of the RTS packet at 60 GHz and transmitseach RTS packet.

While the example in which an end position of the DATA portion of theRTS packet at 5 GHz is coincident with the start position ofBeamTrainingField of the RTS packet at 60 GHz is shown in FIG. 3, arelationship between the end position of the DATA portion of the RTSpacket at 5 GHz and the start position of BeamTrainingField of the RTSpacket at 60 GHz is not limited to the example shown in FIG. 3.

Further, the transmission apparatus sets a plurality of transmissionbeam patterns in BeamTrainingField of the RTS packet at 60 GHz andtransmits the RTS packet at 60 GHz. Here, the example in which thetransmission apparatus sets 10 types of transmission beam patterns inBeamTrainingField of the RTS packet at 60 GHz is shown in FIG. 3, but anexample in which the transmission apparatus sets the transmission beampatterns is not limited to the example shown in FIG. 3.

When a plurality of beam patterns are set in the RTS packet at 60 GHz asshown in FIG. 3 (the second transmission request), the RTS packet at 60GHz may be a packet having a wide dynamic range.

The transmission of the RTS packet as shown in FIG. 3 from thetransmission apparatus allows the reception apparatus to specify thestart position of the RTS packet at 60 GHz (the second transmissionrequest) based on the result of receiving the RTS packet at 5 GHz (thefirst transmission request). Further, a process related to specifying ofthe second transmission request in the reception apparatus may berecognized as a synchronization process in the communication apparatus100.

<Synchronization Process According to Embodiment of the PresentInvention>

FIG. 4 is a flow diagram showing an example of the synchronizationprocess in the communication apparatus 100 according to an embodiment ofthe present invention. Hereinafter, the communication apparatus 100Aplaying a role of a reception apparatus will be described as performingthe synchronization process shown in FIG. 4. However, the othercommunication apparatus 100 may similarly perform the process.

The communication apparatus 100A judges whether the first transmissionrequest has been received (S100). Here, the communication apparatus 100Aperforms the judgment of step S100, for example, based on whether anL-STF or L-LTF portion of the RTS packet at 5 GHz shown in FIG. 3 hasbeen detected.

When it is judged in step S100 that the first transmission request hasnot been received, the communication apparatus 100A does not perform theprocess until it is judged that the first transmission request has beenreceived.

Further, when it is judged in step S100 that the first transmissionrequest has been received, the communication apparatus 100A specifiesthe start position of the second transmission request based on the firsttransmission request (S102; synchronization process). Here, thecommunication apparatus 100A specifies the start position of the secondtransmission request (the start position of BeamTrainingField), forexample, based on the start position of the DATA portion of the RTSpacket at 5 GHz shown in FIG. 3.

The communication apparatus 100A may specify the start position of thesecond transmission request, for example, through the process shown inFIG. 4.

Further, a method of specifying the start position of the secondtransmission request in the communication apparatus 100A (or the othercommunication apparatus 100) according to an embodiment of the presentinvention is not limited to the method based on the start position ofthe DATA portion of the RTS packet at 5 GHz shown in FIG. 3. Forexample, a time interval from a predetermined position of the firsttransmission request to the start position of the second transmissionrequest is determined in advance between the transmission apparatus andthe reception apparatus constituting the information process system1000, such that the communication apparatus 100A (reception apparatus)can specify the start position of the second transmission request. Thatis, the determination of the time interval allows the communicationapparatus 100A (reception apparatus) to specify the start position ofthe second transmission request based on the predetermined position ofthe first received transmission request. Here, the predeterminedposition of the first transmission request may include, for example, ahead portion or an end portion of L-STF and a head portion or an endportion of L-LTF of the RTS packet at 5 GHz shown in FIG. 3, but thepresent invention is not limited thereto. Further, in the above case,the transmission apparatus transmitting the signal by the carrier f2having the second frequency (the second transmission request) at apredefined time interval from the predetermined position of the signalby the carrier f1 having the first frequency (the first transmissionrequest) corresponds to the synchronized transmission.

Further, in the information process system 1000, the transmissionapparatus transmits a first transmission request including dataindicating the time interval from the predetermined position of thefirst transmission request to the start position of the secondtransmission request, thereby specifying the start position of thesecond transmission request in the reception apparatus. That is, in theabove case, the communication apparatus 100A (reception apparatus) mayuniquely specify the start position of the second transmission requestbased on the data indicating the time interval included in the firstreceived transmission request. Further, in the above case, thetransmission apparatus transmitting the signal by the carrier f2 havingthe second frequency (the second transmission request) at a predefinedtime interval from the predetermined position of the signal by thecarrier fl having a first frequency (the first transmission request)corresponds to the above synchronized transmission.

Hereinafter, a case in which the communication apparatus 100A (or theother communication apparatus 100) constituting the communication system1000 specifies the start position of the second transmission request,for example, based on the start position of the DATA portion of the RTSpacket at 5 GHz as shown in FIG. 3 will be described by way of example.

Referring back to FIG. 2, an example of a communication process in thecommunication system 1000 according to an embodiment of the presentinvention will be described. The communication apparatus 100A determinesthe requested beam pattern, for example, based on the RTS packet at 60GHz specified by the process shown in FIG. 4.

<Requested Beam Pattern Determination Process according to Embodiment ofthe Present Invention>

FIG. 5 is a flow diagram showing an example of a requested beam patterndetermination process in the communication apparatus 100 according to anembodiment of the present invention. Hereinafter, the communicationapparatus 100A playing a role of a reception apparatus will be describedas performing the requested beam pattern determination process shown inFIG. 5. However, the other communication apparatus 100 may similarlyperform the process.

The communication apparatus 100A sets m to be m=0 (S200). Here, theprocess of step S200 corresponds to initialization of a processingnumber of the transmission beam pattern set in the second transmissionrequest. Accordingly, the m value set in step S200 is not limited to 0.

The communication apparatus 100A derives reception intensity in an m-thtransmission beam pattern included in the second communication request(S202). The communication apparatus 100A records the derived receptionintensity for each transmission beam pattern. Here, the communicationapparatus 100A derives reception power for each transmission beampattern as reception intensity based on the received signal, but thepresent invention is not limited thereto. For example, the communicationapparatus 100A may use an absolute value of the reception power for eachtransmission beam pattern as the reception intensity based on thereceived signal.

When the reception intensity is derived in step S202, the communicationapparatus 100A judges whether reception intensities for all thetransmission beam patterns included in the second communication requesthave been derived (S204).

When it is not judged in step S204 that the reception intensities forall the transmission beam patterns included in the second communicationrequest have been derived, the communication apparatus 100A updates them value to be “m=m+1” (S206). The communication apparatus 100Aiteratively performs the process from step S202.

Further, when it is judged in step S204 that the reception intensitiesfor all the transmission beam patterns included in the secondcommunication request have been derived, the communication apparatus100A determines the requested beam pattern based on the derivedreception intensities (S208). Here, the communication apparatus 100Adetermines, for example, as the requested beam pattern, the transmissionbeam pattern having maximum reception intensity among the transmissionbeam patterns included in the second communication request, but a methodof determining the requested beam pattern in the communication apparatus100A is not limited thereto.

The communication apparatus 100A may determine the requested beampattern based on the plurality of transmission beam patterns included inthe second communication request, for example, through the process shownin FIG. 5. Further, it is understood that the process according to thedetermination of the requested beam pattern in the communicationapparatus 100 according to an embodiment of the present invention is notlimited thereto.

Referring back to FIG. 2, an example of the communication process in thecommunication system 1000 according to an embodiment of the presentinvention will be described. For example, when the requested beampattern is determined through the process shown in FIG. 5, thecommunication apparatus 100A transmits requested beam patternidentification information indicating the requested beam pattern with aCTS (Clear to Send) packet at 5 GHz (notification of completion ofreception preparation) (period b in FIG. 2).

Here, the communication apparatus 100A (or the other communicationapparatus 100) transmits, for example, the requested beam pattern as therequested beam pattern identification information, but the requestedbeam pattern identification information according to an embodiment ofthe present invention is not limited thereto. For example, thecommunication apparatus 100 according to an embodiment of the presentinvention may transmit, for example, an identification number indicatingthe requested beam pattern as the requested beam pattern identificationinformation. Here, the identification number may include, for example, anumber set in the transmission beam pattern corresponding to therequested beam pattern in advance, or a number indicating order ofprocessing the transmission beam pattern corresponding to the requestedbeam pattern, but the present invention is not limited thereto. Thecommunication apparatus 100A (reception apparatus) can reduce a dataamount due to the transmission of the requested beam pattern, forexample, by transmitting the identification number as the requested beampattern identification information. Accordingly, the communicationsystem 1000 can prevent throughput from being degraded due to thetransmission of the requested beam pattern.

The communication apparatus 100B determines the transmission beampattern based on the requested beam pattern identification informationincluded in the received CTS packet at 5 GHz. The communicationapparatus 100B transmits DATA (DATA packet) with the 60 GHz carrier byapplying the determined transmission beam pattern (a period c in FIG.2). Here, the communication apparatus 100B may perform DATA transmissionby the 5 GHz carrier f1 together with DATA transmission by the 60 GHzcarrier f2, as shown in the period c of FIG. 2.

Further, the example in which the communication apparatus 100A(reception apparatus) determines the requested beam pattern based on thereception intensities derived for all the transmission beam patternsincluded in the second communication request and transmits the requestedbeam pattern identification information has been shown, but an apparatusfor determining the requested beam pattern in an embodiment of thepresent invention is not limited to the communication apparatus 100A(reception apparatus). For example, in the information process system1000, the communication apparatus 100B (or the other communicationapparatus 100) playing a role of a transmission apparatus may determinethe requested beam pattern instead of the communication apparatus 100Aplaying a role of a reception apparatus (or the other communicationapparatus 100). The above example will be described in greater detail.The communication apparatus 100A (reception apparatus) transmits, forexample, the respective reception intensities derived for all thetransmission beam patterns included in the second communication request,as the requested beam pattern identification information. Thecommunication apparatus 100B (transmission apparatus) determines therequested beam pattern based on each reception intensity included in thereceived requested beam pattern identification information, anddetermines the transmission beam pattern based on the determinedrequested beam pattern. Even in the above case, the communicationapparatus 100B (transmission apparatus) may determine the transmissionbeam pattern based on the same requested beam pattern as the requestedbeam pattern determined by the communication apparatus 100A (receptionapparatus) in step S208 in FIG. 5. Accordingly, the communicationapparatus 100B (transmission apparatus) may transmit DATA with a 60 GHzcarrier by applying the transmission beam pattern based on the requestedbeam pattern, similar to the case in which the communication apparatus100A (reception apparatus) determines the requested beam pattern.

When the DATA has been received normally, the communication apparatus100A transmits an ACK (ACKnowledgement) packet at 5 GHz to notify thecommunication apparatus 100B that the DATA has been received normally(period d in FIG. 2).

For example, the communication shown in FIG. 2 is performed between thecommunication apparatus 100A and the communication apparatus 100B, suchthat communication by the 60 GHz carrier f2 (faster than communicationby the 5 GHz carrier f1) is stably performed in the communication system1000. Further, it is understood that the communication between thecommunication apparatus 100A and the communication apparatus 100B in thecommunication system 1000 according to an embodiment of the presentinvention is not limited to the example shown in FIG. 2.

[Overview of Automatic Gain Control Approach according to Embodiment ofthe Present Invention]

In the communication system 1000 according to an embodiment of thepresent invention, for example, the communication shown in FIG. 2(communication by the communication process according to an embodimentof the present invention) is performed, such that more reliable datatransmission and reception can be realized by the carrier f2 having thesecond frequency. Here, in communication in the communication system1000 according to an embodiment of the present invention, for example, aplurality of transmission beam patterns are set in the secondtransmission request transmitted from the communication apparatus 100playing a role of a transmission apparatus, as shown in FIG. 3.Accordingly, the second transmission request may be a packet having awide dynamic range.

Here, when the communication apparatus 100 performs automatic gaincontrol at the head of the RTS packet at 60 GHz shown in FIG. 3 (thesecond transmission request) like a conventional communicationapparatus, a very wide dynamic range of the RTS packet causes dataoutside a measurement range to be likely to be generated. In the abovecase, since the communication apparatus 100 cannot derive the receptionintensity normally for each transmission beam pattern included in thesecond transmission request, the communication apparatus 100 cannotdetermine the requested beam pattern from among the plurality oftransmission beam patterns included in the second transmission request.

Here, the communication apparatus 100 processes, for example, the secondtransmission request (an example of the packet) having a dynamic rangethat is wide (likely to be wide) as shown in FIG. 3, for example, usingthe following approaches (1) and (2).

(1) First Approach

When the reception apparatus processes the second received transmissionrequest using the AGC setting value obtained through the automatic gaincontrol at the head of the second transmission request like aconventional communication apparatus, data outside the measurement rangeis likely to be generated. Here, in the communication system 1000, thetransmission apparatus (one communication apparatus 100 transmits thesecond transmission request including an AGC setting value for causingthe reception apparatus (the other communication apparatus 100) toperform the automatic gain control. The reception apparatus performs theautomatic gain control using the AGC setting value included in thesecond transmission request.

Here, the communication apparatus 100 playing a role of the transmissionapparatus transmits the second transmission request in which a pluralityof transmission beam patterns are set. Accordingly, the communicationapparatus 100 playing a role of the transmission apparatus may transmitthe second transmission request in which an AGC setting valuecorresponding to the second transmission request to be transmitted isset based on the plurality of transmission beam patterns included in thesecond transmission request to be transmitted. That is, thecommunication apparatus 100 playing a role of a reception apparatus mayderive reception intensity normally for each transmission beam patternirrespective of the dynamic range of the second transmission request byperforming the automatic gain control using the AGC setting valueincluded in the second transmission request. Accordingly, thecommunication apparatus 100 playing a role of a reception apparatus candetermine the requested beam pattern from among the plurality oftransmission beam patterns included in the second transmission request.

[Example of Second Transmission Request According to First Approach]

FIG. 6 is an illustrative diagram showing an example of the secondtransmission request in which the AGC setting value is set. Here, FIG. 6shows a case in which the first frequency is 5 GHz and the secondfrequency is 60 GHz, as in FIG. 3.

A plurality of transmission beam patterns are set in BeamTrainingFieldof an RTS packet at 60 GHz (the second transmission request) shown inFIG. 6, similar to the RTS packet at 60 GHz shown in FIG. 3. Further, anAGC area in which the AGC setting value is set is also provided inBeamTrainingField of the RTS packet at 60 GHz shown in FIG. 6.

Here, when the AGC setting value is set in a head of BeamTrainingFieldas shown in FIG. 6, the communication apparatus 100 playing a role of areception apparatus performs automatic gain control based on the AGCsetting value. As described above, when the reception apparatus performsthe process based on one AGC setting value set for the plurality oftransmission beam patterns included in the second transmission request,data outside a measurement range is likely to be generated although theAGC setting value is set by the transmission apparatus.

Thus, the communication apparatus 100 playing a role of a transmissionapparatus according to an embodiment of the present invention transmitsthe second transmission request in which a corresponding AGC settingvalue is set for each transmission beam pattern set in the secondtransmission request.

FIG. 7 is an illustrative diagram showing an example of the secondtransmission request in which the AGC setting value is set according toan embodiment of the present invention. Here, FIG. 7 shows a case inwhich the first frequency is 5 GHz and the second frequency is 60 GHz,as in FIG. 3.

A plurality of transmission beam patterns are set in BeamTrainingFieldof an RTS packet at 60 GHz (a second transmission request) shown in FIG.7, similar to the RTS packet at 60 GHz shown in FIG. 3. Further, an AGCarea in which the AGC setting value is set and a BeamTrainingField inwhich a transmission beam pattern is set are provided in eachtransmission beam pattern set in the RTS packet at 60 GHz.

Here, when the AGC setting value is set for each transmission beampattern included in the second transmission request as shown in FIG. 7,the communication apparatus 100 playing a role of a reception apparatusperforms automatic gain control based on the AGC setting value for eachtransmission beam pattern. In the above case, the communicationapparatus 100 playing a role of a reception apparatus corresponds toprocessing of a packet having substantially single directivity.

Accordingly, the communication apparatus 100 playing a role of areception apparatus may derive reception intensity normally for eachtransmission beam pattern irrespective of the dynamic range of thesecond transmission request. Accordingly, the communication apparatus100 playing a role of a reception apparatus can determine a requestedbeam pattern from among the plurality of transmission beam patternsincluded in the second transmission request.

Further, the second transmission request in which the AGC setting valueis set according to an embodiment of the present invention is notlimited to the configuration shown in FIG. 7. For example, thecommunication apparatus 100 playing a role of a transmission apparatusaccording to an embodiment of the present invention may transmit asecond transmission request with a predetermined no signal period (gap)between the transmission beam patterns shown in FIG. 7. In the abovecase, the communication apparatus 100 playing a role of a receptionapparatus can secure more time for deriving the reception intensity foreach transmission beam pattern.

As described above, in the first approach, the communication apparatus100 playing a role of a transmission apparatus transmits, for example,the second transmission request in which the AGC setting value (a firstautomatic gain control setting value) corresponding to each settransmission beam pattern is set, as shown in

FIG. 7. The communication apparatus 100 playing a role of a receptionapparatus performs the automatic gain control for each transmission beampattern based on the AGC setting value corresponding to eachtransmission beam pattern included in the second transmission request.Thus, since the communication apparatus 100 playing a role of areception apparatus can prevent data outside the measurement range frombeing generated despite the width of the dynamic range of the secondtransmission request, the communication apparatus 100 can process thepacket having a wide dynamic range.

Thus, the use of the first approach allows the communication apparatus100 to process a packet having a wide dynamic range in communicationusing the directivity of the antenna.

(Second Approach)

The method by which the communication apparatus 100 performs theautomatic gain control for each transmission beam pattern based on thesecond transmission request in which the AGC setting value is set foreach transmission beam pattern has been shown as the first approach forautomatic gain control in the communication apparatus 100 according toan embodiment of the present invention. However, the method of automaticgain control for the second transmission request (an example of thepacket) having a dynamic range that is wide (likely to be wide)according to an embodiment of the present invention is not limitedthereto. Here, a method of automatic gain control for a secondtransmission request when the AGC setting value is not set in the secondtransmission request will now be described as a second approach forautomatic gain control in the communication apparatus 100 according toan embodiment of the present invention.

FIG. 8 is an illustrative diagram showing an example of a secondtransmission request according to an embodiment of the presentinvention. Here, FIG. 8 shows a case in which the first frequency is 5GHz and the second frequency is 60 GHz, as in FIG. 3.

In an RTS packet at 60 GHz (the second transmission request) shown inFIG. 8, a plurality of transmission beam patterns are set inBeamTrainingField, similar to the RTS packet at 60 GHz shown in FIG. 3.Further, the AGC area according to the first approach as shown in FIG. 7is not provided in the RTS packet at 60 GHz.

In order to process the second transmission request in which the AGCsetting value is not set as shown in FIG. 8, the communication apparatus100 divides a plurality of antennas into a plurality of groups andincludes a plurality of AGC circuits corresponding to the groups.Further, the communication apparatus 100 sets a different AGC settingvalue (a third automatic gain control setting value) for each AGCcircuit corresponding to the group. Setting the different AGC settingvalue for the AGC circuit corresponding to each group in advance allowsthe communication apparatus 100 to make a determination of the requestedbeam pattern that selectively uses the second transmission requestsubjected to the automatic gain control in any AGC circuit. Hereinafter,one, two or more antennas, an analog circuit corresponding to theantenna, and an AGC circuit for processing a signal received by theantenna will be described as constituting one group. Further, it isunderstood that a configuration of the group in the present invention isnot limited thereto.

When the reception intensity of the signal processed by thecommunication apparatus 100 is in a range of 0 [dBm] to −90 [dBm], thecommunication apparatus 100 includes, for example, a plurality ofantennas divided into three groups for receiving a carrier f2 having asecond frequency, and an AGC circuit for each group.

The three groups include, for example, a first group capable ofreceiving a range of 0 [dBm] to −30 [dBm], a second group capable ofreceiving a range of −30 [dBm] to −60 [dBm], and a third group capableof receiving a range of −60 [dBm] to −90 [dBm]. Further, it isunderstood that the number of groups according to an embodiment of thepresent invention is not limited to 3 and the range that can be receivedis not limited thereto.

The communication apparatus 100 covers an entire range (or a wide range)of reception intensity to be processed, through the plurality of groups,such that the communication apparatus 100 can derive reception intensitynormally for each transmission beam pattern based on the secondtransmission request output from the AGC circuit corresponding to anygroup. Accordingly, the communication apparatus 100 can determine therequested beam pattern from among the plurality of transmission beampatterns included in the second transmission request.

Here, an example of the requested beam pattern determination process inthe communication apparatus 100 using the second approach will bedescribed. FIG. 9 is a flow diagram showing an example of the requestedbeam pattern determination process in the communication apparatus 100according to an embodiment of the present invention.

The communication apparatus 100 selects the second transmission requestused for a process based on the second transmission request output fromthe AGC circuit corresponding to each group (S300). Here, the process instep S300 corresponds to a group selection process of selecting a group.

[Group Selection Process According to Embodiment of the PresentInvention]

Here, the group selection process according to an embodiment of thepresent invention will be described. FIG. 10 is an illustrative diagramillustrating an example of the group selection process according to anembodiment of the present invention. Here, FIG. 10 shows a case in whichthe communication apparatus 100 receives the carrier f2 having thesecond frequency with 3 receiving systems (hereinafter, also referred toas “branches”), i.e., in which the communication apparatus 100 has threegroups, each receiving a signal. Further, FIG. 10 shows an example inwhich branch 0 (group 0) serves a range of 0 [dBm] to −30 [dBm], branch1 (group 1) serves a range of −30 [dBm] to −60 [dBm], and branch 2(group 2) serves a range of −60 [dBm] to −90 [dBm].

For example, when the resolution of an AD converter (Analog to DigitalConverter) constituting each group is 10 bits, the communicationapparatus 100 selects one group based on a value p of a signal (p is aninteger; −511≦p≦511) output from the AGC circuit of each group.

More specifically, the communication apparatus 100 derives, for example,an average value p′ of absolute values of values p for each group in apredetermined period and selects a group whose average value p′ iscloser to 256 (a middle point between 0 and 511). This is because whenthe average value p′ is 511, the signal output from the AGC circuit istoo great to be out of range and when the average value p′ is 0, thereceived signal is small. Accordingly, the communication apparatus 100selects group 0 (branch 0) in case 1 of FIG. 10 and selects group 1(branch 1) in case 2. The communication apparatus 100 selects group 2(branch 2) in case 3.

The communication apparatus 100 performs, for example, the above processand selects the group, such that the communication apparatus 100 canselect the second transmission request used for the process based on thesecond transmission request output from the AGC circuit corresponding toeach group. Further, the group selection method according to anembodiment of the present invention is not limited to the above method.

Referring back to FIG. 9, an example of the requested beam patterndetermination process in the communication apparatus 100 using thesecond approach will be described. The communication apparatus 100 setsm to be m=0 (S302), similar to step S200 in FIG. 5. Further, the m valueset in step S302 is not limited to 0.

The communication apparatus 100 derives reception intensity in the m-thtransmission beam pattern included in the second communication request,as in step S202 in FIG. 5 (S304). The communication apparatus 100records the derived reception intensity for each transmission beampattern. Here, the communication apparatus 100 derives reception powerfor each transmission beam pattern based on the received signal, asreception intensity, but the present invention is not limited thereto.For example, the communication apparatus 100 may use an absolute valueof the reception power for each transmission beam pattern based on thereceived signal, as the reception intensity.

When the reception intensity is derived in step S304, the communicationapparatus 100 judges whether reception intensities for all thetransmission beam patterns included in the second communication requesthave been derived, as in step S204 in FIG. 5 (S306).

When it is not judged in step S306 that the reception intensities forall the transmission beam patterns included in the second communicationrequest have been derived, the communication apparatus 100 updates the mvalue to be “m=m 1,” similar to step S206 in FIG. 5 (S308). Thecommunication apparatus 100A iteratively performs the process from stepS304.

Further, when it is judged in step S306 that the reception intensitiesfor all the transmission beam patterns included in the secondcommunication request have been derived, the communication apparatus 100determines the requested beam pattern based on the derived receptionintensities, as in step S208 in FIG. 5 (S310). Here, the communicationapparatus 100 determines, for example, the transmission beam patternhaving maximum reception intensity among the transmission beam patternsincluded in the second communication request, as the requested beampattern. However, the method of determining the requested beam patternin the communication apparatus 100 is not limited thereto.

For example, as shown in FIG. 9, the communication apparatus 100 usingthe second approach selects one second communication request from amongthe second communication requests output from the AGC circuitscorresponding to the respective groups. The communication apparatus 100performs the same process as the requested beam pattern determinationprocess shown in FIG. 5 based on the plurality of transmission beampatterns included in the selected second communication request.Accordingly, the communication apparatus 100 using the second approachcan determine the requested beam pattern based on the second receivedtransmission request. Further, it is understood that the processaccording to the determination of the requested beam pattern in thecommunication apparatus 100 using the second approach is not limited tothe above process.

As described above, in the second approach, the communication apparatus100 divides the plurality of antennas into a plurality of groups andincludes a plurality of AGC circuits corresponding to the groups.Further, the communication apparatus 100 sets a different AGC settingvalue (the third automatic gain control setting value) for each AGCcircuit corresponding to the group. Setting the different AGC settingvalue for the AGC circuit corresponding to each group allows thecommunication apparatus 100 to derive the reception intensity normallyfor each transmission beam pattern using any second transmission requestoutput from the AGC circuit corresponding to each group. Thus, thecommunication apparatus 100 can determine the requested beam patternfrom among the plurality of transmission beam patterns included in thesecond transmission request irrespective of the dynamic range of thesecond transmission request.

Thus, the use of the second approach allows the communication apparatus100 to process a packet having a wide dynamic range in communicationusing the directivities of the antennas.

Further, when the communication apparatus 100 constituting thecommunication system 1000 uses the second approach, the AGC area is notprovided in the second transmission request transmitted from thecommunication apparatus 100 playing a role of a transmission apparatus,as shown in FIG. 8. Accordingly, the communication system 1000 havingthe communication apparatus 100 using the second approach can improvethroughput compared to the communication system 1000 having thecommunication apparatus 100 using the first approach.

In the communication system 1000 according to an embodiment of thepresent invention, each communication apparatus 100 uses, for example,the approaches indicated in (1) and (2) in communication using thecarrier f2 having the second frequency. Accordingly, the communicationapparatus 100 may process a packet having a dynamic range that is wide(likely to be wide), such as the second transmission request as shown inFIG. 3, in communication using the directivities of the antennas.

Next, a configuration of the communication apparatus 100 capable ofrealizing the automatic gain control approach according to an embodimentof the present invention according to an embodiment of the presentinvention will be described. Hereinafter, a communication apparatus thatrealizes approach (1) (the first approach) will be described as a“communication apparatus 100” and a communication apparatus thatrealizes approach (2) (the second approach) will be described as a“communication apparatus 200”.

(Communication Apparatus according to First Embodiment)

FIG. 11 is an illustrative diagram showing an example of a configurationof the communication apparatus 100 according to a first embodiment ofthe present invention.

The communication apparatus 100 includes a first communication unit 102,a second communication unit 104, and a control unit 106. Further, thecommunication apparatus 100 may include, for example, a ROM (Read OnlyMemory; not shown), a RAM (Random Access Memory; not shown), a storageunit (not shown), a manipulation unit (not shown), a display unit (notshown) and the like. In the communication apparatus 100, for example,the respective components may be connected by a bus as a datatransmission line. Here, the ROM stores control data such as a programor an operation parameter used by the control unit 106. The RAM firststores, for example, a program executed by the control unit 106.

The storage unit (not shown) is a storage means included in thecommunication apparatus 100, and stores a variety of data such asvarious data or applications. Here, the storage unit (not shown) mayinclude, for example, a magnetic recording medium such as a hard disk ora nonvolatile memory such as a flash memory, but the present inventionis not limited thereto.

The manipulation unit (not shown) is a manipulation means included inthe communication apparatus 100 for enabling a manipulation by a user.The communication apparatus 100 may perform a process desired by a userby including the manipulation unit (not shown). Here, the manipulationunit (not shown) may include, for example, a manipulation inputapparatus such as a keyboard or a mouse, or buttons, direction keys, arotatable selector such as a jog dial, or a combination thereof, but thepresent invention is not limited thereto.

The display unit (not shown) is a display means included in thecommunication apparatus 100 and displays various information on adisplay screen.

The screen displayed on the display screen of the display unit (notshown) may include, for example, a manipulation screen for causing adesired operation to be performed on the communication apparatus 100, ora screen indicating a communication state. Here, the display unit (notshown) may include, for example, an LCD (liquid crystal display) or anorganic EL display (organic electroluminescence display or an OLEDdisplay (organic light emitting diode display)), but the presentinvention is not limited thereto.

The first communication unit 102 is a first communication means includedin the communication apparatus 100 and performs wireless communicationwith an external apparatus using a carrier fl having a first frequency.Further, the first communication unit 102 includes a first communicationantenna 110, a first analog signal processing unit 112, and a firstsignal conversion unit 114.

The first communication antenna 110 transmits a signal by the carrier f1having the first frequency to one, two or more external apparatuses, andreceives the signal by the carrier f1 having the first frequencytransmitted from the external apparatus. Hereinafter, the signaltransmitted from the first communication antenna 110 may be referred toa “first transmission signal” and the signal received by the firstcommunication antenna 110 may be referred to a “first reception signal.”

The first analog signal processing unit 112 processes the firstreception signal (analog signal) received by the first communicationantenna 110 and delivers a resultant signal to the first signalconversion unit 114. Further, the first analog signal processing unit112 processes a signal (analog signal) delivered from the first signalconversion unit 114 and causes the first transmission signal to betransmitted from the first communication antenna 110. Here, a process inthe first analog signal processing unit 112 may include, for example,amplification of each signal or noise removal, but the process is notlimited thereto. Further, the first analog signal processing unit 112includes, for example, an integrated circuit having various circuitssuch as an amplifier or a low pass filter integrated therein.

The first signal conversion unit 114 converts a signal (analog signal)corresponding to the first reception signal delivered from the firstanalog signal processing unit 112 into a digital signal, and deliversthe digital signal to the control unit 106 (more specifically, a firstcommunication processing unit 122, which will be described below).Further, the first signal conversion unit 114 delivers a signal (digitalsignal) corresponding to the first transmission signal delivered fromthe control unit 106 (more specifically, the first communicationprocessing unit 122, which will be described) to the first analog signalprocessing unit 112. Here, the first signal conversion unit 114includes, for example, an AD converter and a DA converter (Digital toAnalog Converter), but is not limited thereto.

The first communication unit 102 can perform wireless communication withan external apparatus using the carrier fl having the first frequency byincluding the first communication antenna 110, the first analog signalprocessing unit 112, and the first signal conversion unit 114.

The second communication unit 104 is a second communication meansincluded in the communication apparatus 100, and performs wirelesscommunication with an external apparatus using a carrier f2 having asecond frequency. Further, the second communication unit 104 includes asecond communication antenna 116, a second analog signal processing unit118, and a second signal conversion unit 120.

The second communication antenna 116 includes a plurality ofcommunication antennas, and transmits a signal by the carrier f2 havingthe second frequency to one, two or more external apparatuses andreceives the signal by the carrier f2 having the second frequencytransmitted from the external apparatuses. Hereinafter, a signaltransmitted from the second communication antenna 116 may be referred toas a “second transmission signal” and a signal received by the secondcommunication antenna 116 may be referred to as a “second receptionsignal.”

The second analog signal processing unit 118 processes the secondreception signal (analog signal) received by each communication antennaconstituting the second communication antenna 116 and delivers thesecond reception signal to the second signal conversion unit 120.Further, the second analog signal processing unit 118 processes a signal(analog signal) delivered from the second signal conversion unit 120 andcauses the second transmission signal to be transmitted from eachcommunication antenna constituting the second communication antenna 116.Here, a process in the second analog signal processing unit 118 mayinclude, for example, amplification of each signal, or noise removal,but the process is not limited thereto. Further, the second analogsignal processing unit 118 includes, for example, an integrated circuithaving various circuits such as an amplifier or a low pass filterintegrated therein, similar to the first analog signal processing unit112.

The second signal conversion unit 120 converts a signal (analog signal)corresponding to the second reception signal delivered from the secondanalog signal processing unit 118 into a digital signal, and deliversthe digital signal to the control unit 106 (more specifically, a secondcommunication processing unit 124 which will be described below).Further, the second signal conversion unit 120 delivers a signal(digital signal) corresponding to the second transmission signaldelivered from the control unit 106 (more specifically, the secondcommunication processing unit 124 which will be described below) to thesecond analog signal processing unit 118. Here, the second signalconversion unit 120 includes, for example, an AD converter and a DAconverter, similar to the first signal conversion unit 114, but thesecond signal conversion unit 120 is not limited thereto.

The second communication unit 104 can perform wireless communicationwith an external apparatus using the carrier f2 having the secondfrequency by including the second communication antenna 116, the secondanalog signal processing unit 118, and the second signal conversion unit120.

The control unit 106 includes, for example, an MPU (Micro ProcessingUnit) or an integrated circuit having various processing circuitsintegrated therein, and controls the entire communication apparatus 100.Further, the control unit 106 includes the first communicationprocessing unit 122 and the second communication processing unit 124 andplays a leading role of performing the above-described communicationprocess according to an embodiment of the present invention.

The first communication processing unit 122 processes the firstreception signal delivered from the first communication unit 102 andtransmits the first transmission signal to the first communication unit102. Here, the first communication processing unit 122 may perform theprocess in conjunction with the second communication processing unit124. For example, the first communication processing unit 122 transmitsthe first transmission signal according to a transmission command fromthe second communication processing unit 124 to the first communicationunit 102.

[Example of Processing First Reception Signal in First CommunicationProcessing Unit 122]

Here, an example of processing the first reception signal in the firstcommunication processing unit 122 will be described. The firstcommunication processing unit 122 generates information indicatingreception initiation of the second transmission request (an example ofthe second reception signal), for example, based on the firsttransmission request (an example of the first reception signal)delivered from the first communication unit 102, and delivers thegenerated information indicating the reception initiation to the secondcommunication processing unit 124.

Here, the information indicating reception initiation is a trigger toinitiate the synchronization process in the second communicationprocessing unit 124. The information indicating reception initiation mayinclude, for example, packet position information indicating a positionof a predetermined packet included in the first transmission request orinformation indicating a position when a predetermined time interval haselapsed from a predetermined position of the first transmission request,but the present invention is not limited thereto. Hereinafter, thepacket position information will be described as the informationindicating reception initiation by way of example. Here, the packetposition information may include, for example, a pulse signal indicatingthat the position of the predetermined packet of the first transmissionrequest has been detected, but the present invention is not limitedthereto. For example, the packet position information according to anembodiment of the present invention may be any signal or data capable ofplaying a role of a trigger for the synchronization process. Further,other information indicating reception initiation according to anembodiment of the present invention may be realized by the same signalor data as the packet position information.

Further, for example, when the requested beam pattern identificationinformation is delivered from the first communication unit 102, thefirst communication processing unit 122 delivers the requested beampattern identification information to the second communicationprocessing unit 124.

The first communication processing unit 122, for example, performs theprocessing as described above, as processing of the first receptionsignal. Further, processing of the first reception signal in the firstcommunication processing unit 122 is not limited thereto.

The second communication processing unit 124 processes the secondreception signal delivered from the second communication unit 104, andtransmits the second transmission signal to the second communicationunit 104. Here, the second communication processing unit 124 may performthe processing in conjunction with the first communication processingunit 122. For example, the second communication processing unit 124performs the processing, for example, based on the packet positioninformation delivered from the first communication processing unit 122or the requested beam pattern identification information.

[Example of Configuration of Second Communication Processing Unit 124]

Here, a configuration of the second communication processing unit 124will be described in greater detail. FIG. 12 is an illustrative diagramshowing an example of the configuration of the second communicationprocessing unit 124 according to the first embodiment of the presentinvention. In FIG. 12, the second signal conversion unit 120constituting the second communication unit 104 is also shown.

The second communication processing unit 124 includes a synchronizationunit 130, an automatic gain control unit 132, a setting value storageunit 134, a decoding unit 136, a processing unit 138, an encoding unit140, a beam pattern application unit 142, a reception intensityderivation unit 144, and a requested beam pattern determining unit 146.Here, the second communication processing unit 124 further includes abeam pattern storage unit (not shown) in which information (e.g., aweight coefficient) of a transmission beam pattern for being applied toa signal to be transmitted to an external apparatus is stored.

The synchronization unit 130 specifies a start position of the secondtransmission request based on the packet position information deliveredfrom the first communication processing unit 122. Here, the specifyingof the start position of the second transmission request in thesynchronization unit 130 corresponds to a packet extraction process.

Further, the synchronization unit 130 may deliver a signal indicatingthat the second transmission request has been received, to the receptionintensity derivation unit 144. The delivery of the signal indicatingthat the second transmission request has been received enables thereception intensity derivation unit 144 to selectively perform a processwhen the second transmission request is received.

Further, when the second communication unit 104 receives the DATA shownin FIG. 2, the synchronization unit 130 achieves synchronization withthe process of the first communication processing unit 122, for example,through bit synchronization or character synchronization, but thepresent invention is not limited thereto.

When the delivered signal is the second transmission request, theautomatic gain control unit 132 adjusts a gain of the secondtransmission request for the AGC setting value (the first automatic gaincontrol setting value) set for each transmission beam pattern includedin the second transmission request. Further, the automatic gain controlunit 132 holds each AGC setting value set in the second transmissionrequest in the setting value storage unit 134.

Further, when the delivered signal is not the second transmissionrequest, the automatic gain control unit 132 adjusts a gain of thedelivered signal (a signal corresponding to the second reception signal)based on the AGC setting value (the second automatic gain controlsetting value) stored in the setting value storage unit 134. Here, theautomatic gain control unit 132 performs the automatic gain controlusing the AGC setting value stored in the setting value storage unit 134as a fixed value, but the present invention is not limited thereto. Forexample, the automatic gain control unit 132 may use the AGC settingvalue stored in the setting value storage unit 134 as an initial valueof the automatic gain control.

Further, the automatic gain control unit 132 has, for example, an AGCcircuit including an LNA (Low Noise Amplifier) for performing switchingof a great gain or a VGA (Variable Gain Amplifier) for performingswitching of a smaller gain, but the configuration of the automatic gaincontrol unit 132 is not limited thereto.

The setting value storage unit 134 stores the AGC setting value (thesecond automatic gain control setting value). The AGC setting valuestored in the setting storage unit 134 may include, for example, an AGCsetting value (the first automatic gain control setting value)corresponding to the transmission beam patterns included in the secondtransmission request determined as the requested beam pattern by therequested beam pattern determining unit 146, but the present inventionis not limited thereto.

For example, when the second transmission request is simultaneoustransmission of the transmission beam patterns because series orthogonalor quasi-orthogonal is assigned to each transmission beam pattern, thesetting value storage unit 134 may store an AGC setting value increasingthe gain compared to the AGC setting value corresponding to therequested beam pattern. This is because, for example, when the AGCsetting value acquired from the RTS packet at 60 GHz shown in FIG. 2 isused, reception intensity when the DATA is received is likely to beseveral times the reception intensity when the transmission beam patterncorresponding to the requested beam pattern is received.

Here, the setting value storage unit 134 switches the stored AGC settingvalue to the AGC setting value corresponding to the requested beampattern or the AGC setting value increasing the gain, for example, byjudging a type of the second transmission request, but a method ofswitching the stored AGC setting value in the setting value storage unit134 is not limited thereto. For example, the setting value storage unit134 may perform the switching based on a signal indicating the type ofthe second transmission request delivered from another component (e.g.,the processing unit 138). Further, it is understood that it may bedefined in advance whether the AGC setting value corresponding to therequested beam pattern or the AGC setting value increasing the gain isto be stored in the setting value storage unit 134 according to anembodiment of the present invention.

The setting value storage unit 134 also holds each AGC setting value(the first automatic gain control setting value) set in the secondtransmission request delivered from the automatic gain control unit 132.

Further, the setting value storage unit 134 is a recording medium forstoring and holding the AGC setting value and includes, for example, avolatile memory and a nonvolatile memory, but the present invention isnot limited thereto. Here, each AGC setting value (the first automaticgain control setting value) set in the second transmission requestdelivered from the automatic gain control unit 132 is held, for example,in the volatile memory, such as an SRAM (Static Random Access Memory).Further, the AGC setting value (the second automatic gain controlsetting value) corresponding to the requested beam pattern is stored,for example, in the nonvolatile memory, such as a flash memory.

The decoding unit 136 performs, for example, demodulation or demappingbased on the signal having the adjusted gain (digital signal) outputfrom the automatic gain control unit 132. Here, a demodulation scheme inthe decoding unit 136 may include, for example, an OFDM (OrthogonalFrequency Division Multiplexing) modulation scheme, but the presentinvention is not limited thereto.

The processing unit 138 plays a role of performing various signalprocessing in the second communication processing unit 124.

[Example of Signal Processing in Processing Unit 138]

Here, an example of signal processing in the processing unit 138 will bedescribed. The processing unit 138 processes the signal delivered fromthe decoding unit 136, and delivers a signal resulting from theprocessing to the encoding unit 140.

Further, the processing unit 138 performs a process of transmitting atransmission request in which one or two or more transmission beampatterns are set in one packet and the AGC setting value is set for eachtransmission beam pattern, to the second communication unit 104. Here,the process in the processing unit 138 may include a process ofcontrolling the beam pattern application unit 142, which is performed insynchronization with signal delivery to the encoding unit 140, but thepresent invention is not limited thereto. Further, the above process inthe processing unit 138 is performed, for example, when thecommunication apparatus 100 plays a role of a transmission apparatus.The transmission request according to the process in the processing unit138 may include, for example, the RTS packet at 60 GHz shown in FIG. 7,but the present invention is not limited thereto. Here, the transmissionrequest according to the process in the processing unit 138 correspondsto the second transmission request in the other communication apparatus100 constituting the communication system 1000.

Further, the processing unit 138, for example, transmits the requestedbeam pattern identification information based on the requested beampattern determined by the requested beam pattern determining unit 146 toan external apparatus having transmitted the second transmission requestvia the first communication processing unit 122. The process in theprocessing unit 138 is performed, for example, when the communicationapparatus 100 plays a role of a reception apparatus.

Here, an external apparatus having transmitted the second transmissionrequest, to which the processing unit 138 has transmitted the requestedbeam pattern identification information, corresponds to an externalapparatus having transmitted the second transmission request that therequested beam pattern determining unit 146 uses to determine therequested beam pattern.

Further, the configuration in which the second communication processingunit 124 includes the requested beam pattern determining unit 146 andthe processing unit 138 that are separate entities is shown in FIG. 12,but the present invention is not limited thereto. For example, in thesecond communication processing unit 124 according to an embodiment ofthe present invention, the processing unit 138 may play a role of therequested beam pattern determining unit 146 which will be describedbelow.

The processing unit 138 performs, for example, the process as describedabove, as signal processing. Further, the signal processing in theprocessing unit 138 is not limited thereto.

The encoding unit 140 performs, for example, modulation or mapping basedon the signal delivered from the processing unit 138. Here, a modulationscheme in the decoding unit 136 may include, for example, an OFDMmodulation scheme, but the present invention is not limited thereto.

The beam pattern application unit 142 selectively weights the signal tobe transmitted from the second communication unit 104 and setsdirectivity (or non-directivity) in the signal to be transmitted fromthe second communication unit 104. Here, weighting the signal in thebeam pattern application unit 142 may include, for example, complexmultiplication of a weight coefficient (a complex number) correspondingto the transmission beam pattern to be applied to the signal.

Further, the beam pattern application unit 142 may multiply a signal tobe transmitted by a weight coefficient corresponding to the requestedbeam pattern identification information transmitted from an externalapparatus (application of the requested beam pattern based on therequested beam pattern identification information. Here, the requestedbeam pattern identification information delivered to the beam patternapplication unit 142 is, for example, delivered from the firstcommunication processing unit 122, based on the CTS packet having thefirst frequency, shown in FIG. 2, received by the first communicationunit 102. Further, the beam pattern application unit 142 acquires theweight coefficient corresponding to the requested beam patternidentification information, for example, by referencing a beam patternstorage unit (not shown), but a method of acquiring the weightcoefficient corresponding to the requested beam pattern identificationinformation in the beam pattern application unit 142 is not limitedthereto. The beam pattern application unit 142 multiplying the signal tobe transmitted by the weight coefficient corresponding to the requestedbeam pattern identification information enables the communicationapparatus 200 to transmit the carrier f2 having the second frequency towhich a transmission beam pattern desired by an external apparatus hasbeen applied.

The reception intensity derivation unit 144 derives reception intensityfor each transmission beam pattern based on the second transmissionrequest delivered from the automatic gain control unit 132 and the AGCsetting value set in the second transmission request held in the settingvalue storage unit 134. Here, the reception intensity derivation unit144 derives the AGC setting value (or an adjustment value correspondingto the AGC setting value), e.g., the adjusted reception intensity, but amethod of deriving the adjusted reception intensity in the receptionintensity derivation unit 144 is not limited thereto. Further, thereception intensity derivation unit 144 may selectively derive thereception intensity, for example, based on the signal indicating thatthe second transmission request delivered from the synchronization unit130 has been received.

The requested beam pattern determining unit 146 determines the requestedbeam pattern based on the derivation result from the reception intensityderivation unit 144.

Further, the requested beam pattern determining unit 146 delivers, tothe setting value storage unit 134, the AGC setting value set for thetransmission beam pattern corresponding to the determined requested beampattern among the AGC setting values set in the second transmissionrequest.

The second communication processing unit 124 processes the secondreception signal delivered from the second communication unit 104 andtransmits the second transmission signal to the second communicationunit 104, for example, by having the configuration shown in FIG. 12.Further, the second communication processing unit 124, for example,performs the above-described communication process in conjunction withthe first communication processing unit 122 by having the configurationshown in FIG. 12.

[Modified Example of Second Signal Processing Unit according to FirstEmbodiment]

Further, a configuration of the second communication processing unit 124according to the first embodiment of the present invention is notlimited to the configuration shown in FIG. 12. FIG. 13 is anillustrative diagram showing an example of a configuration of a secondcommunication processing unit 124′ according to a modified example ofthe first embodiment of the present invention.

Referring to FIG. 13, the second communication processing unit 124′basically has the same configuration as the second communicationprocessing unit 124 shown in FIG. 12, but further includes a beampattern application unit 148 before the decoding unit 136.

The beam pattern application unit 148 weights a signal delivered fromthe automatic gain control unit 132 to set directivity (ornon-directivity) in the signal. Here, weighting the signal in the beampattern application unit 148 may include, for example, complexmultiplication of a weight coefficient (corresponding to the requestedbeam pattern complex number) corresponding to the requested beampattern.

The second communication processing unit 124′ may apply a reception beampattern to the second reception signal received by the secondcommunication unit 104 by including the beam pattern application unit148. Accordingly, the second communication processing unit 124′ canobtain a greater gain than the second communication processing unit 124shown in FIG. 12.

Further, since the second communication processing unit 124′ basicallyhas the same configuration as the second communication processing unit124 shown in FIG. 12, the second communication processing unit 124′ canrealize the same function as the second communication processing unit124 shown in FIG. 12.

The control unit 106 can realize the first approach described above andthe communication process according to an embodiment of the presentinvention by including the first communication processing unit 122 andthe second communication processing unit 124 (or the secondcommunication processing unit 124′).

The communication apparatus 100, for example, can realize theabove-described automatic gain control approach (the first approach)according to an embodiment of the present invention and thecommunication process according to an embodiment of the presentinvention, by means of the configuration shown in FIG. 10.

As described above, the communication apparatus 100 according to thefirst embodiment performs the automatic gain control on eachtransmission beam pattern based on the AGC setting value correspondingto each transmission beam pattern included in the second transmissionrequest transmitted by the carrier f2 having the second frequency.Accordingly, since the communication apparatus 100 can process a packethaving substantially single directivity despite a great dynamic range ofthe second received transmission request, it is possible to preventgeneration of data outside the measurement range. Accordingly, thecommunication apparatus 100 can process a packet having a wide dynamicrange in communication using the directivities of the antennas.

Further, since the communication apparatus 100 can process a packethaving a wide dynamic range, a communication process capable ofachieving stability of communication using the directivities of theantennas according to an embodiment of the present invention can berealized.

(Communication Apparatus According to Second Embodiment)

Next, the communication apparatus 200 capable of realizing theabove-described approach (2) (the second approach) according to a secondembodiment of the present invention will be described. FIG. 14 is anillustrative diagram showing an example a configuration of thecommunication apparatus 200 according to the second embodiment of thepresent invention.

The communication apparatus 200 includes a first communication unit 102,a second communication unit 202, and a control unit 204. Further, thecommunication apparatus 200 may include, for example, a ROM (not shown),a RAM (not shown), a storage unit (not shown), a manipulation unit (notshown), a display unit (not shown) and the like. In the communicationapparatus 200, for example, the respective components may be connectedby a bus, as a data transmission line.

The first communication unit 102 is a first communication means includedin the communication apparatus 200, and performs wireless communicationwith an external apparatus using the carrier f1 having the firstfrequency. Further, the first communication unit 102 has the samefunction and configuration as the first communication unit 102 shown inFIG. 11.

The second communication unit 202 is a second communication meansincluded in the communication apparatus 200, and performs wirelesscommunication with an external apparatus using the carrier f2 having thesecond frequency. Further, the second communication unit 202 includes asecond communication antenna 210, a second analog signal processing unit212, and a second signal conversion unit 214.

The second communication antenna 210, the second analog signalprocessing unit 212, and the second signal conversion unit 214 basicallyhave the same function and configuration as the second communicationantenna 116, the second analog signal processing unit 118, and thesecond signal conversion unit 120 shown in FIG. 11.

Here, a difference between the second communication unit 202 and thesecond communication unit 104 shown in FIG. 11 according to the firstembodiment is that the respective components of the second communicationunit 202 are grouped. For example, when the second communicationantennas 210 are divided into three groups, the second analog signalprocessing unit 212 and the second signal conversion unit 214 have threesignal processing systems corresponding to the respective groups. Here,for example, when the second communication antenna 210 includes 30communication antennas, the communication apparatus 200 groups thecommunication antennas uniformly in number, but the present invention isnot limited thereto. For example, the communication apparatus 200 groupsthe communication antennas differently in number, e.g., 10, 15 and 5.

Hereinafter, the communication apparatus 200 will be described asincluding the second communication unit 202 having a configuration inwhich communication antennas are divided into three groups. Further, itis understood that the grouping according to an embodiment of thepresent invention is not limited to three groups.

The control unit 204 includes, for example, an MPU or an integratedcircuit having various processing circuits integrated therein, andcontrols the entire communication apparatus 200. Further, the controlunit 204 includes a first communication processing unit 122 and a secondcommunication processing unit 216, and plays a leading role ofperforming the above-described communication process according to anembodiment of the present invention.

The first communication processing unit 122 has the same function andconfiguration as the first communication processing unit 122 shown inFIG. 11.

The second communication processing unit 216 processes the secondreception signal delivered for each group from the second communicationunit 202 and transmits the second transmission signal for each group tothe second communication unit 202. Here, the second communicationprocessing unit 216 may perform the process in conjunction with thefirst communication processing unit 122, similar to the secondcommunication processing unit 124 shown in FIG. 11.

[Example of Configuration of Second Communication Processing Unit 216]

Here, a configuration of the second communication processing unit 216will be described in greater detail. FIG. 15 is an illustrative diagramshowing an example of the configuration of the second communicationprocessing unit 216 according to the second embodiment of the presentinvention. In FIG. 15, the second signal conversion unit 214constituting the second communication unit 202 is also shown.

The second communication processing unit 124 includes a synchronizationunit 130, an automatic gain control unit 230, a setting value storageunit 232, a decoding unit 136, a processing unit 138, an encoding unit140, a beam pattern application unit 142, a group selection unit 234, areception intensity derivation unit 236, and a requested beam patterndetermining unit 238. Here, the second communication processing unit 216may further include a beam pattern storage unit (not shown) in whichinformation of a transmission beam pattern for being applied to a signalto be transmitted to an external apparatus is stored

The synchronization unit 130, the decoding unit 136, the processing unit138, the encoding unit 140, and the beam pattern application unit 142have the same function and configuration as the corresponding componentsshown in FIG. 12.

The automatic gain control unit 230 includes an AGC circuitcorresponding to each group, and adjusts a gain of a signal deliveredfor each group (a signal corresponding to the second reception signal).Here, each AGC circuit constituting the automatic gain control unit 230adjusts the gain of the delivered signal based on a different AGCsetting value (a third automatic gain control setting value) for eachAGC circuit stored in the setting value storage unit 232 in advance.

Further, each AGC circuit constituting the automatic gain control unit230 performs automatic gain control using the AGC setting value storedin the setting value storage unit 232 as a fixed value, but an AGCsetting value used for the automatic gain control by each AGC circuitconstituting the automatic gain control unit 230 is not limited thereto.For example, each AGC circuit constituting the automatic gain controlunit 230 may use the AGC setting value stored in the setting valuestorage unit 232 as an initial value of the automatic gain control.

Further, each AGC circuit constituting the automatic gain control unit230 includes, for example, an LNA for performing switching of a greatgain or a VGA for performing switching of a smaller gain, but thepresent invention is not limited thereto.

The setting value storage unit 232 for storing the AGC setting value (athird automatic gain control setting value) for each AGC circuitconstituting the automatic gain control unit 230 includes, for example,a nonvolatile memory such as a flash memory as a recording medium forstoring the AGC setting value, but the recording medium included in thesetting value storage unit 232 is not limited thereto.

The group selection unit 234 selects one group based on receptionintensity of a signal for each group delivered from the automatic gaincontrol unit 230. The group selection unit 234 delivers information ofthe selection result (e.g., an index number indicating the group) to thereception intensity derivation unit 236.

Further, a configuration in which the group selection unit 234 deliversthe selection result information to the reception intensity derivationunit 236 is shown in FIG. 15, but a target to which the group selectionunit 234 delivers the selection result information is not limitedthereto. For example, the group selection unit 234 according to anembodiment of the present invention may also deliver the selectionresult information to the processing unit 138. The delivery of theselection result information enables the processing unit 138 toselectively process a signal corresponding to a group indicated by theselection result information among the signals for the groups deliveredfrom the decoding unit 136.

The reception intensity derivation unit 236 selectively processes onesecond transmission request among the second transmission requests forthe groups delivered from the automatic gain control unit 230 based onthe selection result information delivered from the group selection unit234. More specifically, the reception intensity derivation unit 236derives reception intensity for each transmission beam pattern based onthe second transmission request corresponding to the group indicated bythe selection result information and the AGC setting value stored in thesetting value storage unit 232.

Further, the reception intensity derivation unit 236 may selectivelyderive the reception intensity, for example, based on the signalindicating that the second transmission request delivered from thesynchronization unit 130 has been received.

The requested beam pattern determining unit 238 determines the requestedbeam pattern based on the derivation result from the reception intensityderivation unit 236.

The second communication processing unit 216, for example, processes thesecond reception signal for each group delivered from the secondcommunication unit 202 and transmits the second transmission signal foreach group to the second communication unit 202 by having theconfiguration shown in FIG. 15. Further, the second communicationprocessing unit 216, for example, performs the above-describedcommunication process in conjunction with the first communicationprocessing unit 122 by having the configuration shown in FIG. 15.

[Modified Example of Second Signal Processing Unit According to SecondEmbodiment]

Further, a configuration of the second communication processing unit 216according to the second embodiment of the present invention is notlimited to the configuration shown in FIG. 15. FIG. 16 is anillustrative diagram showing an example of a configuration of the secondcommunication processing unit 216′ according to a modified example ofthe second embodiment of the present invention.

Referring to FIG. 16, the second communication processing unit 216′basically has the same configuration as the second communicationprocessing unit 216 shown in FIG. 15, but further includes a beampattern application unit 240 before the decoding unit 136 and the groupselection unit 234.

The beam pattern application unit 240 weights a signal for each groupdelivered from the automatic gain control unit 230, and sets directivity(or non-directivity) in the signal. Here, weighting the signal in thebeam pattern application unit 240 may include, for example, complexmultiplication of a weight coefficient (complex number) corresponding tothe requested beam pattern.

The second communication processing unit 216′ may apply a reception beampattern to the second reception signal for each group received by thesecond communication unit 104 by including the beam pattern applicationunit 240. Accordingly, the second communication processing unit 216′ canobtain a greater gain compared to the second communication processingunit 216 shown in FIG. 15.

Further, since the second communication processing unit 216′ basicallyhas the same configuration as the second communication processing unit216 shown in FIG. 15, the second communication processing unit 216′ canrealize the same function as the second communication processing unit216 shown in FIG. 15.

The control unit 204 can realize the second approach described above andthe communication process according to the embodiment of the presentinvention by including the first communication processing unit 122 andthe second communication processing unit 216 (or the secondcommunication processing unit 216′).

The communication apparatus 200 can realize, for example, theabove-described automatic gain control approach (the second approach)according to the embodiment of the present invention and thecommunication process according to the embodiment of the presentinvention, by using the configuration shown in FIG. 14.

As described above, the communication apparatus 200 according to thesecond embodiment divides a plurality of antennas into a plurality ofgroups, and includes a plurality of AGC circuits corresponding to thegroups. Further, the communication apparatus 200 sets a different AGCsetting value (the third automatic gain control setting value) for eachAGC circuit corresponding to the group. Here, setting the different AGCsetting value in the AGC circuit corresponding to each group enables thecommunication apparatus 200 to cover an entire range (or wide range) ofthe reception intensity to be processed in the communication by thecarrier f2 having the second frequency. Thus, the communicationapparatus 200 can determine the requested beam pattern from among theplurality of transmission beam patterns based on the second transmissionrequest output from the AGC circuit corresponding to any groupirrespective of the dynamic range of the second transmission request.Accordingly, the communication apparatus 200 can process a packet havinga wide dynamic range in communication using the directivity of theantenna.

Further, since the communication apparatus 200 can process a packethaving a wide dynamic range, a communication process capable ofachieving stability of communication using the directivities of theantennas according to an embodiment of the present invention can berealized.

While the communication apparatus 100 and the communication apparatus200 have been described by way of example as the embodiments of thepresent invention, the embodiment of the present invention is notlimited to such forms. The embodiment of the present invention may beapplied to, for example, various apparatuses having a communicationfunction, such as a computer such as a PC, a portable communicationapparatus such as a portable telephone, and a portable game machine.

The preferred embodiments of the present invention have been describedabove with reference to the accompanying drawings, whilst the presentinvention is not limited to the above examples, of course. A personskilled in the art may find various alternations and modificationswithin the scope of the appended claims, and it should be understoodthat they will naturally come under the technical scope of the presentinvention.

REFERENCE SIGNS LIST

100, 100A, 100B, 100C, 200 communication apparatus

102 first communication unit

104, 202 second communication unit

106, 204 control unit

110 first communication antenna

112 first analog signal processing unit

114 first signal conversion unit

116, 210 second communication antenna

118, 212 second analog signal processing unit

120, 214 second signal conversion unit

122 first communication processing unit

124, 124′, 216, 216′ second communication processing unit

130 synchronization unit

132, 230 automatic gain control unit

134, 232 setting value storage unit

136 decoding unit

138 processing unit

140 encoding unit

142, 148, 240 beam pattern application unit

144, 236 reception intensity derivation unit

146, 238 requested beam pattern determining unit

234 group selection unit

1000 communication system

1. A communication apparatus comprising: a first communication unit forperforming wireless communication with an external apparatus using acarrier having a first frequency; a second communication unit having aplurality of antennas, for performing wireless communication with anexternal apparatus using a carrier having a second frequency having astronger directivity and a higher propagation loss than the carrierhaving the first frequency; a first communication processing unit forprocessing a signal received by the first communication unit and causingthe first communication unit to transmit a signal; and a secondcommunication processing unit for processing a signal received by thesecond communication unit and causing the second communication unit totransmit a signal, wherein the second communication processing unitincludes a synchronization unit for specifying a start position of asecond transmission request in which a plurality of transmission beampatterns are set in one packet, on the basis of information indicatingreception initiation delivered from the first communication processingunit based on a first transmission request received by the firstcommunication unit, the second transmission request being received bythe second communication unit; and an automatic gain control unit forperforming automatic gain control on each transmission beam patternbased on a first automatic gain control setting value corresponding toeach transmission beam pattern, the first automatic gain control settingvalue being included in the second transmission request specified by thesynchronization unit.
 2. The communication apparatus according to claim1, further comprising: a reception intensity derivation unit forderiving reception intensity for each transmission beam pattern based onthe second transmission request output from the automatic gain controlunit; and a requested beam pattern determining unit for determining arequested beam pattern to be transmitted to an external apparatus havingtransmitted the second transmission request from among the plurality oftransmission beam patterns set in the second transmission request, basedon a derivation result from the reception intensity derivation unit. 3.The communication apparatus according to claim 2, further comprising asetting value storage unit for storing a second automatic gain controlsetting value corresponding to the requested beam pattern based on afirst automatic gain control setting value corresponding to therequested beam pattern, wherein the automatic gain control unit performsautomatic gain control based on the second automatic gain control valuewhen the second transmission request is not specified by thesynchronization unit.
 4. The communication apparatus according to claim3, wherein the automatic gain control unit performs the automatic gaincontrol using the first automatic gain control setting value or thesecond automatic gain control setting value as a fixed value or aninitial value.
 5. The communication apparatus according to claim 3,wherein the setting value storage unit stores the second automatic gaincontrol setting value having a higher set gain than the first automaticgain control setting value corresponding to the requested beam pattern.6. The communication apparatus according to claim 3, wherein the settingvalue storage unit stores the first automatic gain control setting valuecorresponding to the requested beam pattern as the second automatic gaincontrol setting value.
 7. The communication apparatus according to claim2, wherein a predetermined no signal period is set between therespective transmission beam patterns among the plurality oftransmission beam patterns set in the second transmission request. 8.The communication apparatus according to claim 2, further comprising aprocessing unit for causing to transmit requested beam patternidentification information indicating the requested beam pattern to anexternal apparatus having transmitted the second transmission requestvia the first communication processing unit.
 9. A communicationapparatus comprising: a first communication unit for performing wirelesscommunication with an external apparatus using a carrier having a firstfrequency; a second communication unit having a plurality of antennasdivided into a plurality of groups, for performing wirelesscommunication with an external apparatus using a carrier having a secondfrequency having a stronger directivity and a higher propagation lossthan the carrier having the first frequency; a first communicationprocessing unit for processing a signal received by the firstcommunication unit and causing the first communication unit to transmita signal; and a second communication processing unit for processing asignal received by the second communication unit and causing the secondcommunication unit to transmit a signal, wherein the secondcommunication processing unit includes a synchronization unit forspecifying a start position of a second transmission request in which aplurality of transmission beam patterns are set in one packet, on thebasis of information indicating reception initiation delivered from thefirst communication processing unit based on a first transmissionrequest received by the first communication unit, the secondtransmission request being received by the second communication unit;and an automatic gain control unit for performing, for each group,automatic gain control on the transmission beam pattern set in eachsecond transmission request received for each group based on a thirddifferent automatic gain control setting value set for each group. 10.The communication apparatus according to claim 9, further comprising: agroup selection unit for selecting one group based on the secondtransmission request for each group output from the automatic gaincontrol unit; a reception intensity derivation unit for derivingreception intensity for each transmission beam pattern based on thesecond transmission request corresponding to the group selected by thegroup selection unit, the second transmission request being output fromthe automatic gain control unit; and a requested beam patterndetermining unit for determining a requested beam pattern to betransmitted to an external apparatus having transmitted the secondtransmission request from among the plurality of transmission beampatterns set in the second transmission request based on a derivationresult from the reception intensity derivation unit.
 11. An automaticgain control method comprising the step of specifying a position of apredetermined packet based on a first transmission request transmittedfrom an external apparatus using a carrier having a first frequency;specifying a start position of a second transmission request in which aplurality of transmission beam patterns defining beam-shaped directivityof a signal to be transmitted are set in one packet based on thespecified position of the predetermined packet, the second transmissionrequest being transmitted from the external apparatus using a carrierhaving a second frequency having a stronger directivity and a higherpropagation loss than the carrier having the first frequency; andperforming automatic gain control for each transmission beam patternbased on an automatic gain control setting value corresponding to eachtransmission beam pattern, the automatic gain control setting valuebeing included in the specified second transmission request.